When Dr. De Meirleir first sees patients with chronic fatigue syndrome they often have cold hands, cold feet and low blood pressure – even in people who are overweight – which is, as he put it…’highly abnormal.’ Their heart rates are also increased (10-12 beats a minute faster than in healthy people).

Welcome to chronic fatigue syndrome, the disorder in which the seemingly paradoxical is commonplace. Low blood pressure and high heart rates when standing indicate a condition called ‘POTS’ (postural orthostatic tachycardia syndrome).Blood pressure often drops as one stands (it should increase), while heart rate increases dramatically (up to 30 beats more/minute). (Right here, whether you have POTS or not, you have a capsule of the cardiovascular system problems in this disorder – the heart rate is increased but everything else, stroke volume, contractility, filling – is reduced when the system is put under stress.)

Nervous System Is One Culprit

Dr. De Meirleir described these problems as being more of a nervous system (autonomic nervous system) than a blood flow problem and noted that when patients get really ‘vagal’ their heart rate can drop low enough so that they lose consciousness. Getting more to the heart of the matter he identified ‘vaso-active’ (blood vessel affecting) substances such as hydrogen sulfide, nitric oxide and carbon dioxide that cause a permanent increase in the size of the larger blood vessels in ME/CFS patients. As those blood vessels become flaccid, the blood pressure drops forcing the small blood vessels tighten up in an attempt to squeeze blood to the organs and muscles. Dilated blood vessels, low blood pressure, and low blood volume are often found in chronic fatigue syndrome.

A Diagnostic Test

Using Marian Lemle’s hydrogen sulfide theory. Dr. De Meirleir devised a hydrogen sulfide test he believes is diagnostic for ME/CFS. These and other vaso-active substances are being studied in ME/CFS. (We should find out a lot more about them in the not-too-distant future when the results of the NIH-funded Vanderbilt study are released.) Studies have shown that the baroreflex response that regulates blood pressure is underperforming as well; all parts of the cardiovascular system do not appear to be responding as well as they should.

Dr. De Meirleir believes these enlarged blood vessels play a key role in producing the low blood volume, low cardiac filling and low heart pump action in ME/CFS. He noted the heart contractions are less forceful because less force is needed to push out the reduced amount of blood in the heart. Blood volume can be so low in this disorder that the mitral valve will not close properly.The enlarged blood vessels, the low blood volume, and the low blood pressure all interact to reduce blood flow to the muscles and organs, setting up possible metabolic problems in the organs and tissues.

What’s causing these imbalances in the cardiovascular systems of people with ME/CFS?

Pathogens – Dr. De Meirleir referred to Dr. Lerner’s work, suggesting herpesvirus activation plays a role in reducing heart pump activity. While applauding Dr. Lerner’s success in returning the heart to more normal functioning with what Dr. De Meirleir called ’very aggressive’ antiviral treatment, he called the results ‘preliminary’ until they’ve been replicated.

Inflammation is a problem in many disorders, in particular, cardiovascular disorders – and given all these problems it’s hard not to think of ME/CFS as a cardiovascular disorder. Inflammation is the proverbial "elephant in the room" for ME/CFS; we know it’s not good but it’s not particularly well defined. What researchers mean when they say ‘inflammation’ is unclear but it problably involves increased pro-inflammatory cytokine levels, and increased markers of oxidative stress. (Why the inflammation is present is, of course, the big question. Pathogens, toxin leakage from the gut, an impaired antioxidant system, mitochondrial problems, blood flow problems that produce ischemia, etc., could all produce inflammation)

Dr. De Meirleir believes an inflammatory process in ME/CFS releases substances (e.g. vaso-active compounds) that contribute greatly to the cardiovascular problems found in this illness. Over time, some people develop a sensitivity to the very substance (adrenaline, aka epinephrine) that constricts blood vessels. Hormonal factors can also come into play, demonstrating that blood circulation in ME/CFS is a complex subject; one that we’ll certainly be hearing about more in the future.